1. Field of the Invention
The present invention relates to a method for preparing a phosphor and, more particularly, to a method for preparing a phosphor having high luminescent properties and excellent thermal and chemical stability, and a light emitting device using the same.
2. Description of the Related Art
In general, a phosphor is used as a material for converting a particular wavelength of light from various types of light sources into a desired wavelength of light. In particular, among various light sources, a light emitting diode (LED) driven with low power consumption and having excellent light efficiency may be advantageously applied as a backlight of a liquid crystal display (LCD), for vehicle illumination, and as a household illumination system (or a household lighting system). Thus, recently, a phosphor material has come to prominence as a core technology.
Recently, a technique for implementing white light, similar to natural light as defined in CIE color coordinates, is being developed and research into a white LED element for emitting white light is actively ongoing.
The white LED element is manufactured by applying phosphors having an emission spectrum such as blue, green, yellow, red, or the like, to an LED chip having a blue or ultraviolet light source. Various phosphors used herein and the luminous efficiency thereof play an important role in determining the characteristics and efficiency of the white LED element.
In a related art phosphor preparation method, a metal compound for preparing a phosphor is measured, a mixture thereof is formed, and then, a phosphor is prepared by firing the mixture at a high temperature.
However, the phosphor obtained through the firing operation at a high temperature does not have a guaranteed uniform composition distribution and powder of the sintered phosphor may cohere, leading to have a relatively large grain size (or granularity). Thus, in order to obtain a uniform, fine grain size, the sintered phosphor is required to be ground through a grinding process.
Also, when the phosphor is a nitride-based phosphor, it may be difficult to sinter, causing a problem in the process requiring a high pressure condition along with a high temperature firing process.